A common way to build and operate communications networks are by usage of synchronous connections between nodes in a network for transmission of synchronous data streams that can stay synchronous over the whole network. This way of building networks has been used since many years. Yet the speed of the connections has generally increased over time, as well as the various techniques used. The connections are carried by different kind of physical medias, such as both wired solutions based on copper or similar material and optical links, as well as wireless links. Above the physical carrier, various signaling methods and protocols may be used to convey data synchronously.
Synchronous data streams over a network may be carried by SDH (Synchronous Digital Hierarchy), SONET (Synchronous Optical Networking), are a couple of non-limiting examples of technologies for synchronously carrying of data. The synchronous data stream has a bitrate determined by a clock frequency.
From the introduction of digital communication the possible bandwidth increase has so far indicated to be almost infinite, enabling different services for telecommunications, data communications and related services carried by those types of networks. The synchronous connections may meet the required need of bandwidth, quality and distance. However, the synchronicity, which is a feature for synchronous connecting between nodes in a network for transmission of a synchronous data stream, sometimes has drawbacks.
One drawback though may be to just maintain the synchronicity throughout a communications network. Another challenge may be in the interconnection of equipment from different vendors, another challenge may be in the transition between different connections, where the transition may for example include transition in speed or bandwidth. Another challenge may be in intersections between pluralities of connections, just to mention some examples of different challenges.
A trend since some time back is to build communications networks as packet data networks, or asynchronous data networks. Packet data networks may be based on synchronous communication links. Alternatively, packet data networks may be operated as packet data links directly over fiber, such as Ethernet or TCP/IP (Transmission Control Protocol/Internet Protocol). Packet data networks may be built both on synchronous as well as asynchronous links. The synchronicity characteristic is normally maintained over a synchronous network, but may be lost over an asynchronous network. Communications networks based on packet data networks may be as complex to build and operate as synchronous networks, but networks based on synchronous communication in larger scale tend to be more complex to build and operate. It seems further that interoperability issues are better handled in the packet data domain.
In practice different network techniques are used, both for historical reasons, as well as that each individual solution may have its strengths and benefits. It may be further unpractical to rebuild or replace communication infrastructure built over many years. A problem is therefore to handle the transition between different networks, such as synchronous networks and asynchronous networks. Another problem is connecting synchronous networks over asynchronous networks together. Another problem is to take advantage of packet data networks, without losing the benefits of a transmission of a synchronous data stream.